Cobalt Sumcorite

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Cobalt Sumcorite
General and classification
other names

IMA 1999-029

chemical formula
  • Pb (Co, Fe) 2 (AsO 4 ) 2 (H 2 O, OH) 2
  • Pb (Co, Fe 3+ , Ni) 2 (AsO 4 ) 2 2 (H 2 O, OH)
  • PbCo 2 (AsO 4 ) 2 • 2H 2 O
Mineral class
(and possibly department) 		Phosphates, arsenates, vanadates
System no. to Strunz
and to Dana 		8.CG.15 ( 8th edition : VII / C.31)
02/40/09/08
Crystallographic Data
Crystal system monoclinic
Crystal class ; symbol monoclinic prismatic; 2 / m
Space group C 2 / m (No. 12)Template: room group / 12
Lattice parameters a  = 9.097  Å ; b  = 6.313 Å; c  = 7.555 Å
β  = 115.08 °
Formula units Z  = 2
Frequent crystal faces { 2 01}, {001}, { 1 11}
Physical Properties
Mohs hardness 4.5, VHN 25  = 500 ± 50 kg / mm 2
Density (g / cm 3 ) 5.31 (calculated)
Cleavage good after {001}
Break ; Tenacity clamshell; brittle
colour brown to reddish brown
Line color light brown
transparency transparent
shine Diamond luster
Crystal optics
Refractive indices n α  = 1.920
n β  = 1.940
n γ  = 1.980
Birefringence δ = 0.060
Optical character biaxial positive
Axis angle 2V = 70 ° (measured)
Pleochroism strong from X = light brown to Y = red brown to Z = yellow
Other properties
Chemical behavior soluble in warm, dilute hydrochloric acid

Cobalt sumorite is a very rarely occurring mineral from the mineral class of " phosphates , arsenates and vanadates ". It crystallizes in the monoclinic crystal system with the chemical composition Pb (Co, Fe) 2 (AsO 4 ) 2 (H 2 O, OH) 2 and is therefore chemically a water-containing lead - cobalt - iron - arsenate with a variable proportion of additional hydroxide ions .

At its type locality, cobalt sumorite develops rosette-shaped aggregates with a maximum diameter of 2 mm, which are seated on quartz and consist of tabular crystals of up to 0.3 mm in size. The type locality of the mineral are mining heaps in the mining district "Am Roten Berg", 4.8 km southwest of the city center of Schneeberg in the Saxon Ore Mountains , where hematite ores were mined in earlier times .

Etymology and history

Like tsumcorite, cobalt sumorite was named after the Tsumeb Corporation in Tsumeb , Namibia , whose landmark is the “De-Wet Shaft”

As early as 1996, lenticular, red-brown crystals were found on and in mine dumps in the former deposit area "Am Roten Berg" in Schneeberg, which come together to form rosette-shaped aggregates. Originally thought to be hematite, the brown line color prompted an investigation in which the material turned out to be a new, cobalt-dominant representative of the tsumcorite group with Fe: Co: Ni = 1: 2: 1. A nearly identical mineral had already been identified in 1993 by the neighboring Rappold mine in Schneeberg- Neustädtel . After the extensive research required, the new phase was presented to the International Mineralogical Association (IMA), which recognized it as a new mineral in 1999. In 2001 the mineral was described as cobalt sumorite by an international team of scientists led by the German scientist Werner Krause and Herta Effenberger, Heinz-Jürgen Bernhardt and Mirko Martin in the German science magazine “New Yearbook for Mineralogy, Monthly Books”. The authors named the mineral because of its kinship with tsumcorite and the dominance of cobalt on the Me (2) position. Tsumcorit had its name from the Tsum eb Cor poration Limited in recognition of their many years of intensive efforts to special investigation of the mineralogy of the ore deposit of Tsumeb.

The type material for cobalt sumorite (holotype) is listed under catalog no. 80100 (location d 1.1) in the geoscientific collections of the Technical University Bergakademie Freiberg in Freiberg , Germany .

classification

The current classification of the International Mineralogical Association (IMA) counts cobalt sumorite to the tsumcorite group with the general formula Me (1) Me (2) 2 (XO 4 ) 2 (OH, H 2 O) 2 , in which Me (1), Me (2) and X different positions in the structure of the minerals of the tsumcorite group with Me (1) = Pb 2+ , Ca 2+ , Na + , K + and Bi 3+ ; Me (2) = Fe 3+ , Mn 3+ , Cu 2+ , Zn 2+ , Co 2+ , Ni 2+ , Mg 2+ and Al 3+ and X = As 5+ , P 5+ , V 5+ and represent S 6+ . To Tsumcoritgruppe include not only Cobalttsumcorit still Cabalzarit , Cobaltlotharmeyerit , Ferrilotharmeyerit , Gartrellit , Helmutwinklerit , Kaliochalcit , Krettnichit , Lotharmeyerit , Lukrahnit , Manganlotharmeyerit , Mawbyit , Mounanait , Natrochalcit , Nickellotharmeyerit , Nickelschneebergit , Nickeltsumcorit , Phosphogartrellit , Rappoldit , Schneebergit , Thometzekit , Tsumcorit , Yancowinnait and Zinc Gartrellite . Cobalt sumcorite forms together with tsumcorite ( Me (2) = Zn), mawbyite (Fe3 + ) and nickel sumcorite (Ni) the "tsumcorite subgroup".

In the meanwhile outdated, but still in use 8th edition of the mineral systematics according to Strunz , cobalt sumorite belonged to the mineral class of "phosphates, arsenates and vanadates" and there to the department of "water-containing phosphates without foreign anions ", where it belongs together with cabalzarite, cobalt solder armyerite, ferrilotharmeyerite , Gartrellite, Helmutwinklerit, Krettnichit, Lotharmeyerit, Lukrahnit, Manganlotharmeyerit, Mawbyit, Mounanait, Nickellotharmeyerit, Nickelschneebergit, Phosphogartrellite, Rappoldit, Schneebergit, Thometzekit, Tsumcorit and zinc gartrellite-group "Tsumcorit-Nr." VII / C.31 formed.

The 9th edition of Strunz's mineral systematics, which has been in effect since 2001 and is used by the International Mineralogical Association (IMA), also assigns cobalt sumcorite to the category of “phosphates etc. without additional anions; with H 2 O “. However, this is further subdivided according to the relative size of the cations involved and the molar ratio of phosphate, arsenate or vanadate complex to the water of crystallization content , so that the mineral can be classified according to its composition in the subsection “With large and medium-sized cations; RO 4  : H 2 O = 1: 1 "can be found, where together with Cabalzarite, Cobaltlotharmeyerite, Ferrilotharmeyerit, Krettnichit, Lotharmeyerit, Manganlotharmeyerit, Mawbyit, Mounanaite, Nickellotharmeyerit, Nickelschneebergit, Schneebergite, Thometzekit and Tsumcorite the group", Thometzekit and Tsumcorite System no. 8.CG.15 forms.

The systematics of minerals according to Dana , which is mainly used in the English-speaking world , assigns cobalt sumorite to the class of "phosphates, arsenates and vanadates" and there in the department of "water-containing phosphates etc.". Here it is together with helmutwinklerite, mawbyite, nickel snow mountainite, rappoldite, snow mountainite, Thometzekit and tsumcorite in the " Helmutwinklerite subgroup " with the system no. 02/40/09 within the subsection “Phosphates containing water, etc., with A 2+ (B 2+ ) 2 (XO 4 ) × x (H 2 O)”.

Chemism

Seven microprobe analyzes on cobalt sumorite yielded mean values ​​of 34.23% PbO; 9.10% CoO; 5.20% NiO; 0.52% ZnO; 8.42% Fe 2 O 3 ; 0.29% Al 2 O 3 ; 36.49% As 2 O 5 ; 0.06% P 2 O 5 ; 0.09% SO 3 and 4.65% H 2 O (calculated) as well as smaller amounts (<0.05% by weight) CaO, CuO, Bi 2 O 3 and V 2 O 5 . On the basis of ten oxygen atoms , the empirical formula Pb 0.97 (Co 0.77 Fe 3+ 0.67 Ni 0.44 Zn 0.04 Al 0.04 ) Σ = 1.96 (AsO 4 ) was calculated from them 2.01 [(H 2 O) 1.32 (OH) 0.64 ] Σ = 1.96 , which leads to Pb (Co, Fe 3+ ) 2 (AsO 4 ) 2 [(H 2 O, OH)] 2 was idealized.

In the crystals, mixed crystal formation on the Me (2) position with the inclusion of Co, Fe 3+ and Ni as well as a substitution of Ca for Pb on the Me (1) position is widespread. The common occurrence of cobalt and nickel in the corresponding mixed crystals is typical for Schneeberg - pure cobalt or nickel members, on the other hand, are unknown. Furthermore, due to the coupled substitution [ Me (1) 2+ Me (2) 3+ ] ↔ [ Me (1) 3+ Me (2) 2+ ], an (OH): H 2 O) ratio of almost 1: 1 possible. The charge balance in cobalt sumorite requires around 3.3 hydrogen atoms per formula unit, so that (OH) 0.7 and (H 2 O) 1.3 are formally required per formula unit .

Cobalt sumcorite is the co-dominant analogue of the Zn-dominated tsumcorite, the Ni-dominated nickel sumorite and the Fe 3+ -dominated mawbyite. Finally, cobalt sumcorite also forms a mixed crystal row with cobalt solder armeyerite, the cobalt-dominant analogue of the Zn-dominated solder armeyerite.

Crystal structure

Cobalt sumcorite crystallizes in the monoclinic crystal system in the space group C 2 / m (space group no. 12) with the lattice parameters a  = 9.097  Å ; b  = 6.313 Å; c  = 7.555 Å and β = 115.08 ° and two formula units per unit cell . Template: room group / 12

The crystal structure of the cobalt sumcorite is identical to the structure of the other representatives of the tsumcorite group. The Me (2) Φ 6 - octahedra (Φ: O 2− , OH - , H 2 O) have common edges and are arranged as chains stretched in the direction of the b-axis [010]. These chains are shared by corners with AsO 4 - tetrahedra linked to each other, thereby forming layers having the composition Me (2) (AsO 4 ) (OH, H 2 O), which are arranged in parallel (001). The topology of this layer is identical to that in natrochalcite, NaCu 2 (SO 4 ) 2 (H 3 O 2 ). The Pb 2+ cations are located between the layers and ensure the connection between the layers in the direction of the a-axis [100]. The Me (1) position is occupied exclusively by Pb atoms. The Me (2) position is occupied by Co and Fe and, to a lesser extent, also Ni. They are coordinated by the oxygen atoms O (1), O (2) and O (3) in a slightly distorted octahedron.

Cobalt sumcorite is isotypic (isostructural) to the monoclinic representatives of the tsumcorite group such as tsumcorite and natrochalcite.

properties

morphology

Cobalt sumcorite developed on the 5 cm large type step found in 1996 "Am Roten Berg", rosette-shaped aggregates up to 2 mm in diameter, consisting of { 2 01} tabular crystals up to 0.3 mm in size parallel to the b-axis [010] consist. In addition to the supporting form { 2 01}, the basic pinacoid {001} and { 1 11} were also identified on the crystals . Furthermore, rosette-shaped aggregates up to 4 mm in diameter are described, which consist of leafy to lenticular crystals up to almost 1 mm in length. In material from the “Prinz Friedrich” mine near Obersdorf in Siegerland, cobalt sumorite forms ledge-shaped crystals up to 0.5 mm in length, which aggregate into small, tufted groups or lattice-like adhesions.

physical and chemical properties

The crystals of the cobalt sumorite are brown to red-brown, the color of the cobalt sumcorite crystals , on the other hand, is always light brown. The surfaces of the transparent crystals have a diamond-like sheen , which agrees well with the values ​​for light refraction . Very high values ​​for the refraction of light (n α  = 1.920; n β  = 1.940; n γ  = 1.980) and a high value for the birefringence (δ = 0.060) were identified on the crystals of cobalt sumcorite . Under the microscope , the mineral shows a strong pleochroism in transmitted light from X = light brown to Y = red-brown to Z = yellow.

Cobalt sumorite has good cleavage properties according to {001}. Due to its brittleness , however , it breaks in a similar way to quartz , with the fracture surfaces being shell-shaped. With a Mohs hardness of 4.5, the mineral is one of the medium-hard minerals, so it stands between the reference minerals fluorite (hardness 4) and apatite (hardness 5) and, like these, can be easily scratched with a pocket knife more (fluorite) or less (apatite) . The Vickers hardness VHN 25 was determined to be 500 ± 50 kg / mm 2 . The calculated density for cobalt sumorite is 5.31 g / cm³. The mineral does not fluoresce in long or short-wave UV light .

Cobalt Sumcorite dissolves in warm, dilute hydrochloric acid , HCl, without effervescence. Like all Pb-containing representatives of the tsumcorite group, cobalt sumcorite dissolves better in dilute hydrochloric acid than the corresponding Ca-containing species, in this case cobalt solder armeyerite.

Education and Locations

Cobalttsumcorit is a typical secondary mineral , which as the most representative of Tsumcoritgruppe in the oxidation zone of arsenic-rich polymetallic non-ferrous metal - deposits formed. Decomposed galena provided the lead required for mineral formation, Co and Fe 3+ were probably provided during the dissolution of minerals of the skutterudite-nickel-cutterudite mixed crystal series, the arsenic also comes from the decomposition of arsenides (skutterudite-nickel cutterudite). In the material from the “Prinz Friedrich” mine, the cobalt content of the cobalt sumorite comes from the decomposition of the alloklas , Co 1-x Fe x AsS.

The type locality of the cobalt sumcorite is the mining area "Am Roten Berg" near Schneeberg , western Ore Mountains , Saxony , Germany . Paragenesis minerals are quartz , galena, Co- and Ni-containing mawbyite, cobalt solder armyerite, arseniosiderite and plumbogummite . Bismutite and Preisingerite and Scorodite are also given as accompanying minerals .

As a very rare mineral formation, cobalt sumorite could only be described from three sources so far (status 2018). In addition to the type locality of the “Am Roten Berg” mine area, in Schneeberg there is also the “Rappold Fundgrube” on the edge of the Schneeberg-Neustädtel cobalt field and the “Prinz Friedrich” mine near Obersdorf between Wilnsdorf and Siegen in Siegerland , North Rhine-Westphalia .

Occurrences of cobalt sumorite in Austria or Switzerland are therefore not known.

use

Because of its rarity, cobalt sumorite is a mineral species of interest only to mineral collectors.

See also

literature

  • Werner Krause, Herta Effenberger, Heinz-Jürgen Bernhardt, Mirko Martin: Cobalttsumcorite and nickellotharmeyerite, two new minerals from Schneeberg, Germany: description and crystal structure . In: New yearbook for mineralogy, monthly books . tape 2001 , no. 12 , 2001, p. 558-576 .
  • Joseph A. Mandarino: New Minerals . In: The Canadian Mineralogist . tape 40 , no. 4 , 2001, p. 1215 , doi : 10.2113 / gscanmin.40.4.1215 ( rruff.info [PDF; 145 kB ; accessed on June 3, 2018]).

Web links

Individual evidence

  1. ↑ a b c d e f g h i j k l m n o p q r s t u v w x y z aa ab ac ad ae af ag ah ai aj ak al am an ao Werner Krause, Herta Effenberger, Heinz- Jürgen Bernhardt, Mirko Martin: Cobalttsumcorite and nickellotharmeyerite, two new minerals from Schneeberg, Germany: description and crysral structure . In: New yearbook for mineralogy, monthly books . tape 2001 , no. 12 , 2001, p. 558-576 .
  2. ↑ Mindat - Nickellotharmeyerit
  3. ^ IMA / CNMNC List of Mineral Names; March 2018 (PDF 1.65 MB)
  4. ↑ a b c Lutz Schlegel, Reinhard Kleeberg, Nicolas Meisser: Secondary bismuth minerals and other new finds from Schneeberg / Saxony, 1992–1995 . In: Lapis . tape 21 , no. 9 , 1996, pp. 37-41 .
  5. ↑ a b Bruno H. Geier, K. Kautz, G. Müller: Tsumcorite (e) [PbZnFe (AsO 4 ) 2 ] · H 2 O, a new mineral from the oxidation zones of the Tsumeb mine, South West Africa . In: New yearbook for mineralogy, monthly books . tape 1971 , 1971, p. 305-309 .
  6. ^ Type mineral catalog Germany - storage of the holotype stage cobalt sumcorite
  7. ↑ Catalog of Type Mineral Specimens - C. (PDF 131 kB) In: docs.wixstatic.com. Commission on Museums (IMA), December 12, 2018, accessed August 29, 2019 .
  8. ↑ Werner Krause, Klaus Belendorff, Heinz-Jürgen Bernhardt, Catherine McCammon, Herta Effenberger, Werner Mikenda: Crystal chemistry of the tsumcorite-group minerals. New data on ferrilotharmeyerite, tsumcorite, thometzekite, mounanaite, helmutwinklerite, and a redefinition of gartrellite . In: European Journal of Mineralogy . tape 10 , 1998, pp. 179-206 , doi : 10.1127 / ejm / 10/2/0179 .
  9. ↑ Igor V. Pekov, Nikita V. Chukanov, Dmitry A. Varlamov, Dmitry I. Belakovskiy, Anna G. Turchkova, Panagiotis Voudouris, Athanassios Katerinopoulos, Andreas Magganas: Nickeltsumcorite, Pb (Ni, Fe 3+ ) 2 (AsO 4 ) 2 (H 2 O, OH) 2 , a new tsumcorite-group mineral from Lavrion, Greece . In: Mineralogical Magazine . tape 80 , no. 2 , 2016, p. 337–346 , doi : 10.1180 / minmag.2016.080.003 .
  10. ^ Allan Pring, Elizabeth Maud McBriar, William D. Birch: Mawbyite, a new arsenate of lead and iron related to tsumcorite and carminite, from Broken Hill, New South Wales . In: The American Mineralogist . tape 74 , no. 12 , 1989, pp. 1377–1381 ( rruff.info [PDF; 589 kB ; accessed on May 26, 2018]).
  11. ↑ a b Werner Krause, Herta Effenberger, Heinz-Jürgen Bernhardt, Mirko Martin: Cobaltlotharmeyerite, Ca (Co, Fe, Ni) 2 (AsO 4 ) 2 (OH, H 2 O) 2 , a new mineral from Schneeberg, Germany . In: New yearbook for mineralogy, monthly books . tape 1999 , no. 11 , 1999, p. 505-517 .
  12. ↑ Joël Brugger, Sergey V. Krivovichev, Uwe Kolitsch, Nicolas Meisser, Michael Andrut, Stefan Ansermet, Peter C. Burns: Description and crystal structure of manganlotharmeyerite, Ca (Mn 3+ , ◻, Mg) 2 {AsO 4 , [AsO 2 (OH) 2 ]} 2 (OH, H 2 O) 2 from the Starlera Mn deposit, Swiss Alps, and a redefinition of lotharmeyerite . In: The Canadian Mineralogist . tape 40 , no. 4 , 2002, p. 1597–1608 , doi : 10.2113 / gscanmin.40.6.1597 ( rruff.info [PDF; 1.1 MB ; accessed on February 20, 2018]).
  13. ↑ a b c Markus Henrich, Sigismund Hupfer: Kobalttsumcorit from Obersdorf, Siegen . In: Mineral World . tape 23 , no. 3 , 2012, p. 28-31 .
  14. ^ Fritz Schlegel: New discoveries and new determinations from the mountain area Schneeberg / Saxony, 1990–2002 (II) . In: Lapis . tape 27 , no. 7/8 , 2002, p. 67-72 .
  15. ↑ Mindat - Number of localities for nickeltlotharmeyerite
  16. ↑ a b c List of places where cobalt sumorite was found in the Mineralienatlas and Mindat